Dr. Calhoun studies the expression of the iIvGMEDA genes of Escherichia coli K-12, and currently is investigating the origins of the four mRNA's derived from this cluster of five genes. Two of the transcripts, corresponding to the EDA and E genes, are relatively abundant, and the other two transcripts, corresponding to the GMEDA and DA genes, are about 20-fold less abundant. These transcripts appear to be generated by a combination of transcription and processing, and from signals that confer the relative rates of degradation. ;